1. Field of the Invention
This invention relates to a light measuring device, and more particularly to a device for measuring the intensity of illumination at a number of points on a light receiving surface called Charge Transfer Device.
2. Description of the Prior Art
A charge transfer device called CTD for measuring the intensity of illumination at a number of points on a light receiving surface is heretofor used in a television camera, for instance. In the conventional light measuring device of this kind, a number of photoreceptors are arranged in a matrix and an output signal of a desired photoreceptor can be taken out by designating the code of an X-direction multiplexer and a Y-direction multiplexer.
In general, the brightness of the object which is normally to be photographed by a camera is within the range of -3 to 2.0 in terms of EV. Since the brightness changes greatly, the output of the photoreceptor must be log-compressed before used as a contol signal. Therefore, when the CTD is used in a camera, a log-conversion amplifier is usually connected to the output terminal of the Y-direction multiplexer for taking out the output signal of the photoreceptors.
Since the CTD has a number of photoreceptors and X- and Y-direction multiplexers on one chip, the log-conversion amplifiers must be externally connected thereto, which results in increase in the manufacturing cost due to the increased number of assembling steps.